An improved filter or trap for use in a cable system is disclosed in U.S. Pat. No. 5,278,525 to Palinkas, the disclosure of which is incorporated herein by reference. The Palinkas device is illustrated in FIG. 1 and is generally referenced 10. The device includes a pair of housing sections 12 and 13 each of which contains filter components for removing or attenuating signals at selected frequencies so that the selected signals will not reach a subscriber's location in a usable form. The housing sections are coaxially aligned along a common center axis 15 with the adjacent end walls 17 and 18 of the housing sections being mounted in close proximity to one another. An electrical isolation shield 20 is mounted between the housing sections to maintain separation between the two and to prevent flux generated by the filters from crossing over between the housing sections. The isolation shield is a generally disc or plate shaped member having opposed end faces that are typically perpendicularly aligned with reference to the common axis 15. A pair of off-axis keys 21-21 are carried upon each end face of the shield which mate with complementary keyways 22-22 formed in the adjacent end walls of the two housing sections. The two filter housing sections and the isolation shield are, in assembly, contained within a tubular sleeve 25 and suitable gaskets 26 and 27 are provided at the two ends of the sleeve to prevent moisture and other contaminants from passing between the sleeve and the housing sections.
A cut out 29 is provided in the shield which permits an off-axis electrical lead 30 to pass between the housing sections. Housing section 12 is equipped with an end cap 31 having a female threaded connector 33 containing a terminal pin 35 that enables the filter assembly to be coupled to a coaxial cable having a conductor carrying the cable signal or other piece of equipment such as a tap or distribution box. The second housing section 13 contains an end cap 36 having a male threaded connector 37 which contains a connector terminal (not shown) for coupling the filter assembly to another coaxial cable or piece of equipment.
Theft of service has long been a problem in the cable industry. Most distribution boxes or taps servicing most cable systems are readily accessible to the general public. All the signals provided by the network are carried to the tap on the provider's cable. However, only the signals that are paid for by a subscriber are tapped onto the subscribers cable, the remaining signal being blocked or attenuated by filters or traps that are typically located in or near the distribution box.
If a subscriber wishes to gain illegal access to the blocked or attenuated signals, he or she can simply remove the blocking or attenuating filters and connect the subscriber's cable directly to the tap input. This type of tampering with the tap connection is, however, easily detected by a visual inspection of the distribution box.
It has been found, however, that prior art filter assemblies, such as described in the above noted Palinkas patent, can be circumvented in manners that are not easily detected by a visual inspection. This may be achieved by removing the filter assembly from the tap and drilling or otherwise creating a passage running along the commonly shaped axis between the two end connectors of the assembly and bypassing the filter components. The center conductor of a coaxial cable can then be passed through the passage between the connectors to bypass the filter components. The assembly, so altered, is then reinstalled in the distribution box in its original location. A service person inspecting the system can see the filter assembly is in place and without further inspection, it is assumed it is working properly to block or attenuate signal at the tuned frequencies.